Hey guys, over the weekend I was doing some work on my Radiator/water neck. I didn't touch anything but those components, and it wasn't anything major. When I tried to start the car to burp the hoses it got ignition and fired up, but wouldn't stay running. We can tell it has fuel and spark which leaves us thinking it's the mass air flow sensor not getting air to the motor. Anyway I'm in the market for a new one for my 1989 GTUs.

If anyone has any other thoughts on what might be stopping it from starting, let me know. BTW we already checked spark plugs. I put new ones in 5 minutes ago.

 

I still think its the MAF/AFM... how long does it stay running?

 

How does it act once it starts up?
when it dies? Does it sputter to its death? Does it fight to run or just shut down?

The mass air flow sensor on the S5 cant stop air from going into the motor as its a i think whats called a hot wire. No flapper door. Is the car throwing any codes?

here to help.

 

air leak between AFM and the throttle body

 

^You beat me to it. Just run your hand along the intake snorkel. There are a few hoses that attach to it that sometimes just fall off while working nearby.

 

Did you plug your BAC and AWS hoses back into the intake funnel?

 

No, it's not a hot wire.
There's a sliding vane instead of a flapper door but it's still a mechanical potentiometer based system.

 

When you turn the key, it revs to about two grand then cuts completely off. Sounds healthy for a split second then just dies. Doesn't sputter or anything.

 

Vac leak mostlikely. These cars will die if the afm wont stay open. it could be vac lines in your engine also. So look for those. If you got a fogger you could to a leak test..

Mine did the same thing and it was a vac leak. let me guess. If you can get it running its fine when its warm?

 

Starter fluid, spray around, watch the exhaust though.

 

The sudden dying make me think it's the AFM/fuel pump issue.

1) Make sure there is gas in the tank. It happens, don't worry about it.

2) Jumper the fuel pump check connector on the passenger strut tower and see if the car will continue to run. If it does, you need to check your AFM according to the manual. And start spraying around for vacuum leaks.

 

I also have an safc 2

 

I would check for any disconnected hoses on or around the area you were working. Make sure all the hoses are connected on the intake snorkel.

 

Do you hear any noises before it dies, like clicking or anything?

 

Bad coolant temp sensor which won't let you start the car (for safety) or ECU. ZThat is what it was for me.

 

broken ( open ) sensor defaults 80 c command and as such the car will stall out cause it lacks cold corrections and also flags for accelerated warm up
similarly shorted senor
( the green top gets loose and can twist around, shorting the two wires inside )
will read very low resistance and so the ECU may incorrectly see temps in excess of 80 c and cut mixture that will make cold start difficult

still worthy of a look .. but i believe in both situations the engine could be kept running with the throttle if ambient conditions where not excessively cold ..
( if your snowed in then i guess its a good place to look )
however the start then stall described by the OP is very symptomatic of an un-metered air leak . ..

 

is it getting power?

 

Yep, it starts to turn on and everything. My friend thought it might have to do with it, but it still turns on and all settings are auto saved so nothing has changed. No ticking or clicking sounds when it starts. I just revs up, and shuts off. I have a maf map and tester I'm about to put to use. Also have a MAF in the mail.

 

My 86 came with an SAFC 2 and one day it wouldnt stay running. Turned out to be a disconnected wire at the ECU. P.O. twisty tied the wires instead of saudering or using butt connectors.

 

If all else fails,try taking the SAFC out of the equation.
Since I started here,I have been altering cars,left and right,mild to wild.
I jumped from N/A to a Haltech.Stock Ecu to RTEK..
But I never went Safc,and that was because of all the Threads posted in which Guys would complain about them.Trouble due to the SAFC,somehow.
I'm not saying that you join the Crowd,but it is sounding that way.
Either that or your AFM connector is just not Connecting into your AFM.
That would cause the car to be able to start up but just die..time after time.crank,start up die.

 

My old FC flooded all the time, we solved that problem with a switch to the fuel pump, try to remove the fuelpumpfuse, crank it till it dies then put it back and crank it again.

 

Especially if it is the signal wire that connects all the input devices together. Can't remember the pin, but I think it connected several system together.

 

I'm having the same issue right now but mine i found that I hade a bad coil pack, replaced it but the car when i floored it doesn't do anything, and when i accelerate a little it stays running but the second i let it go it shuts off. What could it be? I checked every hose every cable i got fuel spark so dont really know whats happening.

 

try keeping your foot of the gas pedal when you start it up. hold it at 2000 rpm until at normal running temp and let go slowly. if it stays on its the cold start. but also check MAF, TPS, and vacuum leaks

 

I mantained it at two grand for a while but the since I bought it it hasnt had a thermostat so normal oporating conditions are not for my car i checked for vacum leaks and replaced the TPS and the MAF is working properly but im still going to replace it. What other thing could it be?